The field of the invention relates generally to wind turbine generators and, more particularly, to systems and methods for reducing noise generated by wind turbine blades.
Most known wind turbine generators include a rotor having multiple blades. The rotor is sometimes coupled to a housing, or nacelle, that is positioned on top of a base, for example, a tubular tower. At least some known utility grade wind turbines, i.e., wind turbines designed to provide electrical power to a utility grid, include rotor blades having predetermined shapes and dimensions. The rotor blades transform mechanical wind energy into induced blade lift forces that further induce a mechanical rotational torque that drives one or more generators, subsequently generating electric power. A plurality of wind turbine generators in a localized geographic array is typically referred to as a wind farm or a wind park.
During operation of such known wind parks or an individual wind turbine, rotational transiting of the rotor blades through air generates aerodynamic acoustic emissions, or noise. As a consequence, at least some of these known wind parks, or an individual wind turbine, will receive noise receptor devices in their vicinity to measure the noise level. At least some of such measured acoustic noises have a decibel (dB) level that may approach local regulatory levels. To comply with the limits, at least some of the wind turbines of the park, or the individual wind turbine, may need to be put into a noise reduced operation (NRO) mode for a period of time. A wind turbine is less efficient at generating electrical energy when in a NRO mode, but produces less noise. The reduction of noise comes at the cost of annual energy production (AEP). Therefore, it is necessary to avoid the application of NROs to increase AEP.